Findings that point to a toxic effect of artificial sweeteners on gut microbes have been dismissed by an industry body, who said the study could not predict what would happen in real life use of sweeteners.

In a statement, the International Sweeteners Association (ISA) asserted that a strong body of well-designed and robust studies conducted in vivo​ in animals and humans confirmed the safety of low calorie sweeteners.

The Brussels-based organisation added, “The publication does not provide evidence that low calorie sweeteners can be toxic to digestive gut microbes in humans”.​

“Indeed, these findings resulted from an in vitro experiment, which exposed bacteria to very high concentrations of low calorie sweeteners out of the human body. ​

“It is important to mention that these are in vitro testing conditions which could have caused reactions that would not be seen with real-life exposure conditions in humans.”​

Of relevance to the industry is the Israeli and Singapore team’s focus of aspartame, sucralose, saccharine, neotame, advantame, and acesulfame potassium-k, used in the selection of sports supplements tested in the study.

These commercially available supplements, whilst unnamed, appear to be a range of tablet and powder forms to be mixed with either water or skimmed milk.

The researchers commented that while a large variety of sport supplements have been widespread and used routinely by athletes during the last decade their side effects had yet to be fully elucidated.

They believed that this was due to the absence of compelling regulation and considerable variation in concentrations, terminology, and combinations of these products.

Study details ​

Here, the use of modified bioluminescent E. coli​ bacteria were employed, which luminesce when they detected toxicants.

Both induced luminescent signals and bacterial growth were measured and two toxicity response patterns were observed, namely, the induction and inhibition of the bioluminescent signal when the bacteria were exposed to certain concentrations of the artificial sweeteners.

Findings revealed an inhibited toxic response when these strains were exposed to concentrations of sucralose ranging from 1 milligram per millilitre (mg/mL) to 100 mg/mL.

A similar result was observed for neotame in which the E. coli​ strain DPD2544 showed signs of toxicity at 2 mg/mL.

On the other hand, the induction response was observed in its response in saccharin with strains responding to the sweetener concentrations of 5 mg/mL with aspartame showing similar effects at 4 mg/mL and ace-k at 10 mg/mL.

Sweeteners rigorously tested ​

“The results of this study may help in understanding the relative toxicity of artificial sweeteners on E. coli, a sensing model representative of the gut bacteria,”​ the study said.

"This is further evidence that consumption of artificial sweeteners adversely affects gut microbial activity which can cause a wide range of health issues,"​ added Professor Ariel Kushmaro, the John A. Ungar chair in biotechnology in the Avram and Stella Goldstein-Goren department of biotechnology engineering at Ben-Gurion University.

As well as the in vitro​ nature of the experiment, the ISA also drew attention to the processes low calorie sweeteners undergo before being approved for use on the market.

They cited the safety assessments designed by the World Health Organization (WHO), the US Food and Drug Administration (FDA) and the European Food Safety Authority (EFSA).

“Based on extensive testing and a strong body of scientific evidence, regulatory food safety bodies around the world consistently confirm their safety.”​